Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

An apparatus and method for providing selective Hybrid Automatic Repeat
reQuest (HARQ) for a ranging service in a wireless communication system
are provided. A HARQ method includes transmitting, to at least one Mobile
Station (MS), ranging code division information, and if a ranging code is
received from the MS, allocating the MS a resource considering the
ranging code, and if a ranging signal is not received through the
resource allocated to the MS, making a request for retransmission of the
ranging signal to the MS.

Claims:

1. A method for supporting ranging of a Mobile Station (MS) in a Base
Station (BS) of a wireless communication system, the method comprising:
transmitting, to at least one MS, ranging code division information;
receiving a ranging code from the MS; transmitting a resource allocation
message comprising allocated resource information to the MS; and if a
ranging signal is not received from the MS using the resource allocated
to the MS, transmitting a retransmission request message for the ranging
signal corresponding to the ranging code to the MS.

2. The method of claim 1, wherein the transmitting of the ranging code
division information to the at least one MS comprises transmitting a
control message comprising the ranging code division information
distinguished to indicate Hybrid Automatic Repeat reQuest (HARQ) support
or non-support.

3. The method of claim 1, wherein the the resource allocation message
comprises at lease one of a frame number index, the ranging code, a
ranging symbol and a ranging subchannel.

4. The method of claim 1, wherein the ranging signal includes one of a
ranging request message (RNG-REQ) and a bandwidth request message (BR).

5. The method of claim 1, wherein the retransmission request message
comprises the same resource allocation information with the resource
allocation information in the resource allocation message for the ranging
signal, wherein the resource allocation information comprises at lease
one of a frame number index, the ranging code, a ranging symbol and a
ranging subchannel.

6. The method of claim 1, wherein after the transmitting the
retransmission request message, further comprising, receiving a ranging
signal retransmitted from the MS; decoding the received ranging signal by
a soft combining in accordance with Hybrid Automatic Repeat reQuest
(HARQ).

7. A method of ranging in a Mobile Station (MS) of a wireless
communication system, the method comprising: receiving a control message
including a ranging code division information; selecting a ranging code
from among at least two ranging codes comprised in the ranging code
division information, and transmitting the selected ranging code to a
Base Station (BS); receiving a resource allocation message including an
allocated resource information from the BS; transmitting a ranging signal
to the BS using an allocated resource in accordance with the allocated
resource information; and upon receiving a retransmission request message
from the BS, retransmitting the ranging signal to the BS.

9. The method of claim 7, wherein the transmitting of the ranging signal
comprises, if the ranging code comprises an initial ranging code,
transmitting a first ranging request message (RNG-REQ) comprising
identification information of the MS and additionally required resource
request information, to the BS through the allocated resource.

10. The method of claim 7, wherein the resource allocation message
comprises at lease one of a frame number index, the ranging code, a
ranging symbol and a ranging subchannel.

11. The method of claim 7, wherein the ranging signal includes one of a
ranging request message (RNG-REQ) and a bandwidth request message (BR).

12. The method of claim 7, wherein the retransmitting comprises:
identifying whether the MS can retransmit the ranging signalin accordance
with at least one of a number of retransmission of the ranging signal and
a retransmission effective time; and if the MS can retransmit the ranging
signal, retransmitting the ranging signal to the BS.

13. The method of claim 7, wherein the retransmitting comprises: if the
resource allocation information in the resource allocation message of the
ranging signal is the same with the resource allocation information in
the retransmission request message, retransmitting the ranging signal to
the BS using the resource allocation information, wherein the resource
allocation information comprises at lease one of a frame number index,
the ranging code, a ranging symbol and a ranging subchannel.

14. An apparatus for supporting ranging of a Mobile Station (MS) in a
Base Station (BS) of a wireless communication system, the apparatus
comprising: a receiver for receiving a signal; a transmitter for
transmitting a signal; and a controller for controlling to transmit, to
at least one MS, ranging code division information, and if a ranging code
is received via the receiver from the MS, transmit a resource allocation
message including an allocated resource information via the transmitter
to the MS, wherein, if a ranging signal is not received from the MS using
the resource allocated to the MS, the controller transmits a
retransmission request message for the ranging signal corresponding to
the ranging code to the MS.

15. The apparatus of claim 14, wherein the controller transmits, through
the transmitter, a control message comprising the ranging code division
information distinguished to indicate Hybrid Automatic Repeat reQuest
(HARQ) support or non-support.

16. The apparatus of claim 14, wherein the controller, transmits the
resource allocation message comprising at lease one of a frame number
index, the ranging code, a ranging symbol and a ranging subchannel.

17. The apparatus of claim 14, wherein the ranging signal includes one of
a ranging request message (RNG-REQ) and a bandwidth request message (BR).

18. The apparatus of claim 14, wherein the controller transmits the
retransmission request message including the same resource allocation
information with the resource allocation information in the resource
allocation message for the ranging signal to the MS, wherein the resource
allocation information comprises at lease one of a frame number index,
the ranging code, a ranging symbol and a ranging subchannel.

19. The apparatus of claim 14, wherein the controller, upon receiving a
ranging signal retransmitted from the MS via the receiver, decoding the
received ranging signal by a soft combining in accordance with Hybrid
Automatic Repeat reQuest (HARQ).

20. An apparatus of ranging in a Mobile Station (MS) of a wireless
communication system, the apparatus comprising: a receiver for receiving
a signal; a transmitter for transmitting a signal; and a controller for
selecting a ranging code from among at least two ranging codes comprised
in ranging code division information and for controlling to transmit the
selected ranging code to a Base Station (BS) through the transmitter, for
controlling to receive a resource allocation message including resource
allocation information through the receiver from the BS, and for
controlling to transmit a ranging signal to the BS through the
transmitter using a resource according to the resource allocation
message, wherein the controller, upon receiving a retransmission request
message from the BS, controls for retransmitting the ranging signal to
the BS through the transmitter.

21. The apparatus of claim 20, wherein the controller identifies the
ranging code division information in a control message provided from the
BS.

22. The apparatus of claim 20, wherein the controller, if the ranging
code comprises an initial ranging code, controls to transmit a first
ranging request message (RNG-REQ) comprising identification information
of the MS and additionally required resource request information, to the
BS through the allocated resource.

23. The apparatus of claim 20, wherein the ranging signal includes one of
a ranging request message (RNG-REQ) and a bandwidth request message (BR).

24. The apparatus of claim 20, wherein the controller determines whether
the controller can control to retransmit the ranging signal in accordance
with at least one of a number of retransmission of the ranging signal and
a retransmission effective time, and if the controller can control to
retransmit the ranging signal, the controller controls to retransmit the
ranging signal to the BS through the transmitter.

25. The method of claim 20, wherein the resource allocation message
comprises at lease one of a frame number index, the ranging code, a
ranging symbol and a ranging subchannel.

26. The apparatus of claim 20, wherein the controller retransmits the
ranging signal to the BS if the resource allocation information in the
resource allocation message is the same with the resource allocation
information in the retransmission request message, wherein the resource
allocation information comprises at lease one of a frame number index,
the ranging code, a ranging symbol and a ranging subchannel.

Description:

PRIORITY

[0001] This application claims the benefit under 35 U.S.C. §119(a) to
Korean patent applications filed in the Korean Intellectual Property
Office on May 23, 2010 and assigned Serial No. 10-2010-0047798, and on
Jun. 22, 2010 and assigned Serial No. 10-2010-0059027, the entire
disclosures of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an apparatus and method for Hybrid
Automatic Repeat reQuest (HARQ) in a wireless communication system. More
particularly, the present invention relates to an apparatus and method
for supporting HARQ for ranging of a Mobile Station (MS) in the wireless
communication system.

[0004] 2. Description of the Related Art

[0005] In a case where there is not a resource that an MS is allocated
from a Base Station (BS) in a wireless communication system, the MS
transmits any ranging code to the BS.

[0006] In a case where the BS receives the ranging code, the BS cannot
identify the MS having transmitted the ranging code, so the BS allocates
a resource to the MS using resource allocation information that is called
a Code Division Multiple Access (CDMA)_Allocation_Information Element
(IE).

[0007] The MS transmits a ranging request message (RNG-REQ) to the BS
using the resource allocated from the BS.

[0008] However, after the MS and the BS perform a link adaptation
procedure, in a case where the MS transmits the ranging request message
(RNG-REQ) to the BS, there is a problem that, because the BS applies a
robust Modulation and Coding Scheme (MCS) level and repetition to the
transmission of the ranging request message (RNG-REQ) of the MS, a
service range for ranging is restricted.

SUMMARY OF THE INVENTION

[0009] Aspects of the present invention are to address at least the
above-mentioned problems and/or disadvantages and to provide at least the
advantages below. Accordingly, an aspect of the present invention is to
provide an apparatus and method for increasing a service range for
ranging in a wireless communication system.

[0010] Another aspect of the present invention is to provide an apparatus
and method for supporting Hybrid Automatic Repeat reQuest (HARQ) for
ranging of a Mobile Station (MS) in a wireless communication system.

[0011] A further aspect of the present invention is to provide an
apparatus and method for supporting HARQ of a ranging request message
(RNG-REQ), for a HARQ supported MS in a Base Station (BS) of a wireless
communication system.

[0012] Yet another aspect of the present invention is to provide an
apparatus and method for distinguishing, by a ranging code, a HARQ
support MS and a HARQ non-support MS in order to support HARQ of a
ranging request message (RNG-REQ) in a BS of a wireless communication
system.

[0013] Still another aspect of the present invention is to provide an
apparatus and method for supporting HARQ of a ranging request message
(RNG-REQ) in an MS of a wireless communication system.

[0014] The above aspects are achieved by providing an apparatus and method
for providing HARQ for ranging in a wireless communication system.

[0015] According to an aspect of the present invention, a BS operation
method is provided. The method includes transmitting, to at least one MS,
ranging code division information, and if a ranging code is received from
the MS, allocating the MS a resource considering the ranging code, and if
a ranging signal is not received through the resource allocated to the
MS, making a request for retransmission of the ranging signal to the MS.

[0016] According to another aspect of the present invention, an MS
operation method is provided. The method includes identifying ranging
code division information, selecting a ranging code from among at least
two ranging codes comprised in the ranging code division information, and
transmitting the selected ranging code to a BS, being allocated a
resource for the selected ranging code from the BS, transmitting a
ranging signal to the BS through the allocated resource, and if the BS
makes a request for retransmission, retransmitting the ranging signal to
the BS.

[0017] According to a further aspect of the present invention, an MS
apparatus is provided. The apparatus includes a receiver for receiving a
signal, a transmitter for transmitting a signal, and a controller for
transmitting, to at least one MS, ranging code division information, and
if a ranging code is received from the MS, allocating the MS a resource
considering the ranging code, wherein, if a ranging signal is not
received through the resource allocated to the MS, the controller makes a
request for retransmission of the ranging signal, to the MS.

[0018] According to yet another aspect of the present invention, an MS
apparatus is provided. The apparatus includes a receiver for receiving a
signal, a transmitter for transmitting a signal, and a controller for
selecting a ranging code from among at least two ranging codes comprised
in ranging code division information and transmitting the selected
ranging code to a BS through the transmitter, transmitting a ranging
signal to the BS through the transmitter by way of a resource for the
ranging code allocated from the BS, wherein, if the BS makes a request
for retransmission, the controller controls for retransmitting the
ranging signal to the BS through the transmitter.

[0019] Other aspects, advantages, and salient features of the invention
will become apparent to those skilled in the art from the following
detailed description, which, taken in conjunction with the annexed
drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other aspects, features, and advantages of the
present invention will become more apparent from the following
description taken in conjunction with the accompanying drawings in which:

[0021] FIG. 1 is a diagram illustrating a ranging procedure with a Mobile
Station (MS) in a Base Station (BS) according to an exemplary embodiment
of the present invention;

[0022] FIG. 2 is a diagram illustrating a ranging procedure in an MS
according to an exemplary embodiment of the present invention;

[0023] FIG. 3 is a block diagram illustrating an apparatus comprising a BS
according to an exemplary embodiment of the present invention;

[0024] FIG. 4 is a block diagram illustrating an apparatus comprising an
MS according to an exemplary embodiment of the present invention; and

[0025] FIG. 5 is a diagram illustrating a band request header according to
an exemplary embodiment of the present invention.

[0026] Throughout the drawings, it should be noted that like reference
numbers are used to depict the same or similar elements, features, and
structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0027] The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
exemplary embodiments of the invention as defined by the claims and their
equivalents. It includes various specific details to assist in that
understanding but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that
various changes and modifications of the embodiments described herein can
be made without departing from the scope and spirit of the invention. In
addition, descriptions of well-known functions and constructions are
omitted for clarity and conciseness.

[0028] The terms and words used in the following description and claims
are not limited to the bibliographical meanings, but, are merely used by
the inventor to enable a clear and consistent understanding of the
invention. Accordingly, it should be apparent to those skilled in the art
that the following description of exemplary embodiments of the present
invention are provided for illustration purpose only and not for the
purpose of limiting the invention as defined by the appended claims and
their equivalents.

[0029] It is to be understood that the singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a component surface" includes reference
to one or more of such surfaces.

[0030] By the term "substantially" it is meant that the recited
characteristic, parameter, or value need not be achieved exactly, but
that deviations or variations, including for example, tolerances,
measurement error, measurement accuracy limitations and other factors
known to those of skill in the art, may occur in amounts that do not
preclude the effect the characteristic was intended to provide.

[0031] FIGS. 1 through 5, discussed below, and the various exemplary
embodiments used to describe the principles of the present disclosure in
this patent document are by way of illustration only and should not be
construed in any way that would limit the scope of the disclosure. Those
skilled in the art will understand that the principles of the present
disclosure may be implemented in any suitably arranged communications
system. The terms used to describe various embodiments are exemplary. It
should be understood that these are provided to merely aid the
understanding of the description, and that their use and definitions in
no way limit the scope of the invention. Terms first, second, and the
like are used to differentiate between objects having the same
terminology and are in no way intended to represent a chronological
order, unless where explicitly state otherwise. A set is defined as a
non-empty set including at least one element.

[0033] The following description is based on the assumption that a Base
Station (BS) and a Mobile Station (MS) predetermine information for HARQ
of ranging before the ranging.

[0034] FIG. 1 illustrates a ranging procedure with an MS in a BS according
to an exemplary embodiment of the present invention.

[0035] Referring to FIG. 1, in step 101, the BS transmits ranging code
division information to at least one MS that is located in a service
area. For example, the BS transmits an Uplink Channel Descriptor (UCD)
message including the ranging code division information, to the at least
one MS located in the service area. Here, the ranging code division
information is defined for an MS supporting HARQ included in the UCD
message, and can be shown as in Table 1.

[0036] After that, the BS proceeds to step 103 and determines whether a
ranging code is received from an MS located in the service area.

[0037] If it is determined in step 103 that the ranging code is not
received, the BS terminates an algorithm according to the present
invention. In a different example, the BS may return to step 101 and
transmit a UCD message to at least one MS every predefined period.

[0038] In contrast, if it is determined in step 103 that the ranging code
is received, the BS proceeds to step 105 and determines whether the MS
having transmitted the ranging code to the BS supports HARQ depending on
the kind of the received ranging code.

[0039] If it is determined in step 105 that the MS supports HARQ, the BS
proceeds to step 107 and allocates for the MS an UpLink (UL) resource
necessary for transmitting a required parameter for distinguishing MSs.
For example, the BS allocates the MS a resource through which the MS can
transmit its own identification information and Grant Management
SubHeader (GMSH), using a resource allocation message (i.e., a Code
Division Multiple Access (CDMA)_Allocation_Information Element (IE)). At
this time, the BS is not aware of the identification information of the
MS for transmitting the resource allocation message (i.e., the
CDMA_Allocation_IE). Accordingly, the BS configures the
CDMA_Allocation_IE to indicate the MS by way of an index of a ranging
code and a ranging code reception position. If a plurality of ranging
codes are received in the same frame, the BS transmits a
CDMA_Allocation_IE for each ranging code and allocates a UL resource to
each MS. Here, the GMSH represents a subheader that an MS is to use for
making a request for an amount of an additionally required resource
besides a ranging request message (RNG-REQ). Further, the ranging code
reception position can be indicated by a frame number. Here, the
CDMA_Allocation_IE can be configured as in Table 2 below.

[0040] After that, the BS proceeds to step 109 and determines whether a
first ranging request message (RNG-REQ) is received through the UL
resource allocated to the MS.

[0041] If it is determined in step 109 that the first ranging request
message (RNG-REQ) is not received, the BS recognizes that the MS fails in
ranging. Accordingly, the BS returns to step 107 and again allocates the
MS a resource for receiving retransmission of the first ranging request
message (RNG-REQ), through HARQ. For example, the BS allocates the MS the
resource for receiving, from the MS, the retransmission of the first
ranging request message (RNG-REQ), using a CDMA_Allocation_IE. Here, the
CDMA_Allocation_IE represents making a request for retransmission of the
first ranging request message (RNG-REQ) using variables such as frame
number index, a ranging code, a ranging symbol, and a ranging subchannel
shown in Table 2. That is, the variables such as the frame number index,
the ranging code, the ranging symbol, and the ranging subchannel
represent reuse of information on a ranging code that the MS has
transmitted lastly. When a ranging request message is received
retransmitted from the MS, the BS decodes the received ranging request
message by a soft combining in accordance with HARQ.

[0042] In contrast, if it is determined in step 109 that the BS receives
the first ranging request message (RNG-REQ) through the UL resource
allocated to the MS, the BS proceeds to step 111 and transmits a ranging
response message (RNG-RSP) to the MS, in response to the received first
ranging request message (RNG-REQ). Here, the ranging response message
(RNG-RSP) includes a basic Connection IDentifier (CID) and a primary
management CID.

[0043] Next, in step 113, the BS identifies a GMSH of the first ranging
request message (RNG-REQ) to determine whether to allocate an additional
resource to the MS.

[0044] If it is determined in step 113 that the GMSH of the first ranging
request message (RNG-REQ) exists and a PiggyBackRequest of the GMSH is
not equal to `0`, the BS determines to allocate the additional resource
to the MS. So, the BS proceeds to step 115 and allocates the MS an
additional resource that the MS makes a request for through the GMSH. At
this time, the BS transmits additionally allocated resource information
to the MS using a HARQ UL-MAP IE configured as in Table 3 below. That is,
since the BS has allocated the basic CID and the primary management CID
to the MS through the ranging response message (RNG-RSP), the BS
transmits the additionally allocated resource information to the MS using
the HARQ UL-MAP IE configured as in Table 3 below.

[0045] Next, the BS proceeds to step 117 and determines whether a second
ranging request message (RNG-REQ) is received through the UL resource
allocated to the MS.

[0046] If it is determined in step 117 that the second ranging request
message (RNG-REQ) is not received through the UL resource allocated to
the MS, the BS recognizes that the MS fails in transmitting the second
ranging request message (RNG-REQ). So, the BS returns to step 115 and
again allocates the MS a resource for receiving retransmission of the
second ranging request message (RNG-REQ). For example, the BS allocates
the MS the resource for receiving the retransmission of the second
ranging request message (RNG-REQ) using a HARQ UL-MAP IE. At this time,
the BS transmits ACKnowledgement/Negative ACKnowledgement (ACK/NACK)
information of the second ranging request message (RNG-REQ) to the MS,
using an ARQ Identifier_Sequence_Number (AI_SN) of a HARQ subburst IE
included in the HARQ UL-MAP IE. More particularly, in a case where the BS
sets the AI_SN to the same value as an AI_SN within a HARQ subburst IE of
the MS included within a just previous HARQ UL-MAP IE to transmit the
ACK/NACK information to the MS, the MS recognizes that the HARQ UL-MAP IE
is the NACK information of the second ranging request message (RNG-REQ).
Further, the BS may transmit the ACK/NACK information of the second
ranging request message (RNG-REQ) to the MS using a DownLink (DL) HARQ
ACK IE. That is, the BS can indicate a bit of a corresponding MS by `1`
or `0` in a bitmap of the DL HARQ ACK IE to indicate the ACK/NACK
information of the second ranging request message (RNG-REQ).

[0047] In contrast, if it is determined in step 117 that the BS receives a
second ranging request message (RNG-REQ) through the UL resource
allocated to the MS, the BS terminates the algorithm according to the
present invention. At this time, although not illustrated, when the BS
receives the second ranging request message (RNG-REQ), the BS transmits a
second ranging response message (RNG-RSP) to the MS in response to the
second ranging request message (RNG-REQ).

[0048] If it is determined in step 105 that the MS does not support HARQ,
the BS proceeds to step 119 and allocates a resource for a ranging
request message (RNG-REQ) to the MS that has transmitted the ranging code
to the BS.

[0049] After that, the BS proceeds to step 121 and determines whether the
ranging request message (RNG-REQ) is received through the UL resource
allocated to the MS.

[0050] If it is determined in step 121 that the BS does not receive the
ranging request message (RNG-REQ), the BS terminates the algorithm
according to the present invention.

[0051] In contrast, if it is determined in step 121 that the BS receives
the ranging request message (RNG-REQ), the BS proceeds to step 123 and
transmits a ranging response message (RNG-RSP) to the MS, in response to
the ranging request message (RNG-REQ).

[0052] After that, the BS terminates the algorithm according to the
present invention.

[0053] In the aforementioned exemplary embodiment, in a case where a BS
does not receive a first ranging request message (RNG-REQ), the BS again
allocates a resource to the MS using a CDMA_Allocation_IE, for the sake
of HARQ of the first ranging request message (RNG-REQ).

[0054] Further, in a case where the BS does not receive a second ranging
request message (RNG-REQ), the BS again allocates a resource to the MS
using a HARQ UL-MAP IE, for the sake of HARQ of the second ranging
request message (RNG-REQ).

[0055] In another exemplary embodiment, in a case where a BS does not
receive a first ranging request message (RNG-REQ), the BS determines
whether the MS can retransmit the first ranging request message (RNG-REQ)
considering the number of retransmission of the first ranging request
message (RNG-REQ). If it is determined that the MS can retransmit the
first ranging request message (RNG-REQ), the BS again allocates a
resource to the MS using a CDMA_Allocation_IE, for the sake of HARQ of
the first ranging request message (RNG-REQ).

[0056] Further, in a case where the BS does not receive a second ranging
request message (RNG-REQ), the BS determines whether the MS can
retransmit the second ranging request message (RNG-REQ) considering the
number of retransmission of the second ranging request message (RNG-REQ).
If it is determined that the MS can retransmit the second raging request
message, the BS again allocates a resource to the MS using a HARQ UL-MAP
IE, for the sake of HARQ of the second ranging request message (RNG-REQ).

[0057] FIG. 2 illustrates a ranging procedure in an MS according to an
exemplary embodiment of the present invention.

[0058] Referring to FIG. 2, in step 201, the MS identifies ranging code
division information. For example, the MS identifies the ranging code
division information in a UCD message provided from a BS.

[0059] After that, the MS proceeds to step 203 and determines whether it
can support HARQ.

[0060] If it is determined in step 203 that the MS supports HARQ, in step
205, the MS selects a ranging code from among ranging codes supporting
HARQ in the ranging code division information and transmits the selected
ranging code to the BS. At this time, the MS selects a ranging code with
reference to Table 4 below.

TABLE-US-00004
TABLE 4
Type
Name (1 byte) Length Value
Start of ranging codes 155 1 Indicates the starting number, S, of the
group
group of codes used for this UL. If not specified, the
default value shall be set to zero. All the
ranging codes used on this UL shall be
between S and ((S + O + N + M + L) mod 256)
where
N is the number of initial ranging codes
M is the number of periodic ranging codes
L is the number of BR codes
O is the number of HO ranging codes
The range of values is 0 ≦ S ≦ 255.
Handover Ranging Codes 194 1 Number of HO ranging CDMA codes.
Possible values are 0-255
Initial ranging codes 150 1 Number of initial ranging CDMA codes.
Possible values are 0-255
Periodic ranging codes 154 1 Number of periodic ranging CDMA codes.
Possible values are 0-255
Bandwidth request codes 152 1 Number of BR codes. Possible values are 0-
255

[0061] After that, the MS proceeds to step 207 and determines whether
resource allocation information is received from the BS. For example, the
MS determines whether a CDMA_Allocation_IE for the ranging code
transmitted to the BS is received from the BS. At this time, the MS
identifies its own CDMA_Allocation_IE using a frame number index, a
ranging code/ranging symbol, and a ranging subchannel.

[0062] If it is determined in step 207 that the MS does not receive the
resource allocation information from the BS during a constant time, the
MS returns to step 205 again and selects a ranging code from among the
ranging codes supporting HARQ in the ranging code division information
and transmits the selected ranging code to the BS. For another example,
the MS may again transmit, to the BS, the ranging code having been
transmitted to the BS in step 205.

[0063] In contrast, if it is determined in step 207 that the MS receives
the resource allocation information from the BS, the MS does not transmit
a ranging code to the BS during a constant time. For example, in a case
where a frame number index of a CDMA_Allocation_IE is configured with 4
bits, the MS does not transmit the ranging code to the BS during 16
frames after receiving the CDMA_Allocation_IE for the ranging code
transmitted to the BS.

[0064] Further, if it is determined in step 207 that the MS receives the
resource allocation information from the BS, the MS proceeds to step 209
and transmits a first ranging request message (RNG-REQ), which includes
its own identification information and GMSH, to the BS using a resource
allocated from the BS. At this time, the MS can configure the GMSH as in
Table 5 below. Here, the GMSH is positioned before a ranging request
message (RNG-REQ) within a Media Access Control (MAC) Packet Data Unit
(PDU) of the ranging request message (RNG-REQ).

[0065] Next, the MS proceeds to step 211 and determines whether a first
ranging response message (RNG-RSP) is received responsive to the first
ranging request message (RNG-REQ) transmitted to the BS.

[0066] If it is determined in step 211 that the first ranging response
message (RNG-RSP) is not received, the MS proceeds to step 219 and
determines whether the BS makes a request for retransmission of the first
ranging request message (RNG-REQ). For example, the MS determines whether
the same CDMA_Allocation_IE as the CDMA_Allocation_IE received in step
207 is received.

[0067] If it is determined in step 219 that the BS does not make a request
for the retransmission of the first ranging request message (RNG-REQ),
the MS returns to step 211 and determines whether a first ranging
response message (RNG-RSP) is received in response to the transmitted
first ranging request message (RNG-REQ).

[0068] In contrast, if it is determined in step 219 that the MS receives
the same CDMA_Allocation_IE as the CDMA_Allocation_IE received in step
207, the MS recognizes that the BS makes a request for retransmission of
the first ranging request message (RNG-REQ). Accordingly, the MS proceeds
to step 221 and determines whether it can retransmit the first ranging
request message (RNG-REQ). For example, the MS determines whether it can
retransmit the first ranging request message (RNG-REQ) considering the
number of retransmission of the first ranging request message (RNG-REQ).
For another example, the MS can determine whether it can retransmit the
first ranging request message (RNG-REQ) using a T3 timer. That is, in a
case where a frame number index of a CDMA_Allocation_IE is configured
with 4 bits, information of the CDMA_Allocation_IE is valid during 16
frames. Accordingly, the MS can determine whether it can retransmit the
first ranging request message (RNG-REQ) using the T3 timer driven as long
as a 16-frame time. Here, the T3 timer is driven when the MS receives the
CDMA_Allocation_IE in step 207. In a case where the T3 timer expires, the
MS recognizes that it cannot perform retransmission of a first ranging
request message (RNG-REQ).

[0069] In a case where the MS cannot retransmit the first ranging request
message (RNG-REQ), the MS terminates the algorithm according to the
present invention. At this time, the MS may transmit a new ranging code
to the BS or attempt an access to a different BS.

[0070] If it is determined in step 221 that the MS can retransmit the
first ranging request message (RNG-REQ), the MS proceeds to step 223 and
retransmits the first ranging request message (RNG-REQ) to the BS. At
this time, the MS retransmits the first ranging request message (RNG-REQ)
using the resource allocation information provided from the BS through
the CDMA_Allocation_IE in step 219.

[0071] If it is determined in step 211 that the MS receives the first
ranging response message (RNG-RSP), the MS proceeds to step 213 and
determines whether information to be additionally transmitted through
ranging exists. That is, the MS identifies an amount of an additional
request resource annexed to a PiggyBackRequest of the GMSH of the first
ranging request message (RNG-REQ).

[0072] If it is determined in step 213 that the additional request
resource is not annexed to the GMSH or the amount of the additional
request resource annexed to the GMSH is equal to `0`, the MS recognizes
that the ranging is ended. Accordingly, the MS terminates the algorithm
according to the present invention.

[0073] In contrast, if it is determined in step 213 that the amount of the
additional request resource annexed to the GMSH is not equal to `0`, the
MS recognizes that information to be additionally transmitted exists.
Accordingly, the MS proceeds to step 215 and determines whether resource
allocation information for second ranging is received. Here, the resource
allocation information for the second ranging is configured in a form of
a HARQ UL-MAP IE as in Table 3 above.

[0074] If it is determined in step 215 that the resource allocation
information for the second ranging is received, the MS proceeds to step
217 and generates a second ranging request message (RNG-REQ) and
transmits the second ranging request message (RNG-REQ) to the BS.

[0075] Next, the MS proceeds to step 211 and determines whether a ranging
response message (RNG-RSP) is received in response to the second ranging
request message (RNG-REQ). That is, the MS performs HARQ of the second
ranging request message (RNG-REQ) depending on reception or non-reception
of the ranging response message (RNG-RSP) responsive to the second
ranging request message (RNG-REQ).

[0076] If it is determined in step 203 that the MS does not support HARQ,
in step 225, the MS selects a ranging code from among ranging codes not
supporting HARQ in the ranging code division information and transmits
the selected ranging code to the BS.

[0077] Next, the MS proceeds to step 227 and determines whether resource
allocation information is received from the BS. For example, the MS
determines whether a CDMA_Allocation_IE for the transmitted ranging code
is received from the BS. At this time, the MS identifies its own
CDMA_Allocation_IE using a frame number index, a ranging code/ranging
symbol, and a ranging subchannel.

[0078] If it is determined in step 227 that the MS does not receive the
resource allocation information from the BS during a constant time, the
MS returns to step 225 and selects any ranging code among ranging codes
supporting HARQ in the ranging code division information and transmits
the selected ranging code to the BS. For another example, the MS may
again transmit the ranging code having been transmitted to the BS in step
225, to the BS.

[0079] In contrast, if it is determined in step 227 that the MS receives
the resource allocation information from the BS, the MS proceeds to step
229 and transmits a ranging request message (RNG-REQ) to the BS.

[0080] After that, the MS proceeds to step 231 and determines whether a
ranging response message (RNG-RSP) is received from the BS in response to
the ranging request message (RNG-REQ).

[0081] If it is determined in step 231 that the MS does not receive the
ranging response message (RNG-RSP) from the BS during a constant time,
the MS returns to step 225 and selects a ranging code and transmits the
selected ranging code to the BS.

[0082] In contrast, if it is determined in step 231 that the MS receives
the ranging response message (RNG-RSP) from the BS, the MS recognizes
that ranging with the BS is ended, and terminates the algorithm according
to the present invention.

[0083] FIG. 3 is a block diagram illustrating an apparatus comprising a BS
according to the present invention.

[0084] As illustrated in FIG. 3, the BS includes a duplexer 300, a
receiver 302, a message processor 304, a controller 306, a HARQ
controller 308, a message generator 310, and a transmitter 312.

[0085] According to a duplexing scheme, the duplexer 300 transmits a
transmit signal provided from the transmitter 312, through an antenna,
and provides a receive signal from the antenna, to the receiver 302.

[0086] The receiver 302 converts a Radio Frequency (RF) signal provided
from the duplexer 300 into a baseband signal, for demodulation. The
receiver 302 can include an RF processing block, a demodulation block, a
channel decoding block, and the like. Here, the RF processing block
converts an RF signal provided from the duplexer 300 into a baseband
signal. The demodulation block may include a Fast Fourier Transform (FFT)
operator for extracting data load on each subcarrier from a signal
provided from the RF processing block, and the like. The channel decoding
block may include a demodulator, a de-interleaver, a channel decoder, and
the like.

[0087] The message processor 304 extracts control information from a
signal provided from the receiver 302, and provides the control
information to the controller 306. For example, the message processor 304
extracts a ranging code, a first ranging request message (RNG-REQ), a
second ranging request message (RNG-REQ), and the like from a signal
provided from the receiver 302, and provides the extracted ranging code,
first ranging request message (RNG-REQ), and second ranging request
message (RNG-REQ) to the controller 306.

[0088] The controller 306 controls general operation and scheduling of the
BS. For example, in a case where the controller 306 receives a ranging
code from the message processor 304, as illustrated in FIG. 1, the
controller 306 allocates a UL resource for the ranging code. At this
time, according to the control of the HARQ controller 308, the controller
306 can allocate only a minimum resource for transmitting identification
information and a GMSH, to an MS supporting HARQ.

[0089] Further, according to the control of the HARQ controller 308, the
controller 306 may allocate a resource for receiving retransmission of a
first ranging request message (RNG-REQ) or allocate a resource for a
second ranging request message (RNG-REQ).

[0090] Depending on the kind of a ranging code provided from the message
processor 304, the HARQ controller 308 determines whether the MS having
transmitted the ranging code supports HARQ. If the MS supports HARQ, the
HARQ controller 308 controls the controller 306 to allocate only a
minimum resource for transmitting the identification information and
GMSH, to the MS supporting HARQ.

[0091] Further, in a case where the controller 306 does not receive a
first ranging request message (RNG-REQ) through a UL resource allocated
to an MS supporting HARQ, the HARQ controller 308 controls the controller
306 to allocate the MS a resource for receiving retransmission of the
first ranging request message (RNG-REQ). When a ranging request message
is received retransmitted from the MS, the BS decodes the received
ranging request message by a soft combining in accordance with HARQ

[0092] In a case where a resource amount for which the MS makes a request
to transmit a second ranging request message (RNG-REQ) through a GMSH of
a first ranging request message (RNG-REQ) provided from the message
processor 304 is identified, the HARQ controller 308 controls the
controller 306 to allocate an additional resource for ranging.

[0093] According to the control of the controller 306, the message
generator 310 generates a control message to be transmitted to an MS. For
example, according to the control of the controller 306, the message
generator 310 generates a UCD message including ranging code division
information. For another example, according to the control of the
controller 306, the message generator 310 generates a resource allocation
message of a CDMA_Allocation_IE form of Table 2 including resource
allocation information for a first ranging request message (RNG-REQ). For
further example, according to the control of the controller 306, the
message generator 310 generates a resource allocation message of a HARQ
UL-MAP IE form of Table 3 including resource allocation information for a
second ranging request message (RNG-REQ).

[0094] The transmitter 312 encodes data to be transmitted to an MS and a
control message provided from the message generator 310, converts the
encoded data and control message into an RF signal, and transmits the RF
signal to the duplexer 300. For example, the transmitter 312 can include
a channel encoding block, a modulation block, an RF processing block, and
the like. Here, the channel encoding block may include a modulator, an
interleaver, a channel encoder, and the like. The modulation block may
include an Inverse Fast Fourier Transform (IFFT) operator for mapping a
signal provided from the channel encoding block to each subcarrier, and
the like. The RF processing block converts a baseband signal provided
from the modulation block into an RF signal, and outputs the RF signal to
the duplexer 300.

[0095] In the aforementioned apparatus, the controller 306, a protocol
controller, can perform a function of the HARQ controller 308. These are
separately constructed and shown in order to distinguish and describe
respective functions in the present invention. Thus, in an actual
realization, construction can be such that all the functions are
processed in the controller 306.

[0096] FIG. 4 is a block diagram illustrating a construction of an MS
according to an exemplary embodiment of the present invention.

[0097] Referring to FIG. 4, the MS includes a duplexer 400, a receiver
402, a message processor 404, a controller 406, a message generator 408,
and a transmitter 410.

[0098] According to a duplexing scheme, the duplexer 400 transmits a
transmit signal provided from the transmitter 410, through an antenna,
and provides a received signal from the antenna, to the receiver 402.

[0099] The receiver 402 converts an RF signal provided from the duplexer
400 into a baseband signal, for demodulation. The receiver 402 can
include an RF processing block, a demodulation block, a channel decoding
block, and the like. Here, the RF processing block converts an RF signal
provided from the duplexer 400 into a baseband signal. The demodulation
block may include an FFT operator for extracting data load on each
subcarrier from a signal provided from the RF processing block, and the
like. The channel decoding block may include a demodulator, a
de-interleaver, a channel decoder, and the like.

[0100] The message processor 404 extracts control information from a
signal provided from the receiver 402, and provides the control
information to the controller 406. For example, the message processor 404
extracts a UCD message, a resource allocation message and the like from a
signal provided from the receiver 402, and provides the extracted UCD
message, resource allocation message, and the like to the controller 406.
Here, the resource allocation message includes a CDMA_Allocation_IE and a
HARQ UL-MAP IE.

[0101] The controller 406 controls general operation and scheduling of the
MS. For example, the controller 406 identifies ranging code division
information in a UCD message provided from the message processor 404.

[0102] In a case where the controller 406 transmits a ranging code, the
controller 406 controls to select the ranging code according to HARQ
support or non-support and transmit the selected ranging code to a BS.
Further, as illustrated in FIG. 2, the controller 406 controls to
transmit a first ranging request message (RNG-REQ) or a second ranging
request message (RNG-REQ) through a UL resource provided from the BS.

[0103] According to the control of the controller 406, the message
generator 408 generates a control message to be transmitted to a BS. For
example, the message generator 408 generates a message for transmitting a
ranging code selected in the controller 406, to the BS. For another
example, according to the control of the controller 406, the message
generator 408 generates a first ranging request message. At this time, in
a case where the MS supports HARQ, the message generator 408 may generate
a first ranging request message including a GMSH as in Table 5 above. For
further example, according to the control of the controller 406, the
message generator 408 may generate a second ranging request message.

[0104] The transmitter 410 encodes data to be transmitted to the BS and a
control message provided from the message generator 408, converts the
encoded data and control message into an RF signal, and transmits the RF
signal to the duplexer 400. For example, the transmitter 410 can include
a channel encoding block, a modulation block, an RF processing block, and
the like. Here, the channel encoding block may include a modulator, an
interleaver, a channel encoder, and the like. The modulation block may
include an IFFT operator for mapping a signal provided from the channel
encoding block to each subcarrier, and the like. The RF processing block
converts a baseband signal provided from the modulation block into an RF
signal, and outputs the RF signal to the duplexer 400.

[0105] Although not illustrated, the MS may further include a timer for
identifying the number of retransmission of a ranging request message
(RNG-REQ). For example, in a case where a frame number index of a
CDMA_Allocation_IE is configured with 4 bits, the timer is driven as long
as a 16-frame time so as to indicate 16 frames during which information
of the CDMA_Allocation_IE is valid. Here, the timer is driven when
initially receiving the CDMA_Allocation_IE.

[0106] In the aforementioned exemplary embodiment, a BS allocates a UL
resource to an MS through a CDMA_Allocation_IE. If the MS supports HARQ,
the MS transmits a HARQ block through the UL resource determined through
the CDMA_Allocation_IE. At this time, for HARQ, unlike a general burst,
the HARQ block is configured in a form in which HARQ Cyclic Redundancy
Check (CRC)-16 is added to a MAC PDU. For example, in a case of
transmitting a ranging request message (RNG-REQ), the ranging request
message (RNG-REQ) is configured in a form in which HARQ CRC-16 is
combined to the back of a MAC PDU. Here, the MAC PDU is configured in a
form in which a generic MAC header and a MAC Service Data Unit (SDU) are
combined with each other. The MAC SDU includes a GMSH, a ranging request
message, and CRC-32.

[0107] In another exemplary embodiment, if an MS supports HARQ, the MS may
configure and transmit a HARQ block in a form of a general burst. That
is, the MS can configure a HARQ block with only a MAC PDU without adding
HARQ CRC-16 to the MAC PDU. For example, the MS can configure a ranging
request message (RNG-REQ) with no addition of HARQ CRC-16.

[0108] In this case, a BS identifies CRC-32 included in a MAC SDU of a
ranging request message (RNG-REQ) instead of HARQ CRC-16, to identify the
occurrence or non-occurrence of an error of the ranging request message
(RNG-REQ). At this time, even when the ranging request message (RNG-REQ)
is not received, the BS can recognize that an error occurs in the ranging
request message (RNG-REQ). If the error occurs in the ranging request
message (RNG-REQ), the BS may reallocate a UL resource to the MS as in
step 109 of FIG. 1. At this time, after the BS initially allocates the MS
a UL resource for the ranging request message (RNG-REQ), the BS can
reallocate a resource for the ranging request message (RNG-REQ) only
during 16 frames. Here, in a case where the BS reallocates a resource
using a CDMA_Allocation_IE, the BS may configure the CDMA_Allocation_IE
for reallocating the resource, as in Table 2 above.

[0109] As described above, a wireless communication system configures a
ranging request message (RNG-REQ) instead of using HARQ CRC-16 in order
to reduce an overhead for HARQ transmission. That is, an MS configures a
first ranging request message (RNG-REQ) instead of using the HARQ CRC-16.
However, the MS may not use a HARQ transmission scheme omitting HARQ
CRC-16 for a second ranging request message (RNG-REQ). That is, the
second ranging request message (RNG-REQ) can be transmitted using a HARQ
UL-MAP IE, because the second ranging request message (RNG-REQ) uses a
primary management CID or basic CID included in a first ranging response
message (RNG-RSP) responsive to the first ranging request message
(RNG-REQ). Accordingly, the second ranging request message (RNG-REQ) can
be transmitted using an original HARQ transmission scheme not omitting
the HARQ CRC-16.

[0110] In the aforementioned exemplary embodiment, a wireless
communication system selectively applies HARQ to a ranging request
message (RNG-REQ) depending on HARQ support or non-support of an MS.

[0111] In another exemplary embodiment, a wireless communication system
may selectively apply HARQ to a Session Border Control-REQuest (SBC-REQ)
message or a band request message depending on HARQ support or
non-support of an MS.

[0112] In a case where the wireless communication system selectively
applies the HARQ to the band request message, the wireless communication
system may apply a HARQ transmission scheme omitting HARQ CRC-16 to the
band request message. That is, an MS supporting HARQ may transmit the
band request message using a transmission scheme not supporting HARQ. For
example, in a case where the MS supporting HARQ makes a request for a
band, the MS transmits a band request ranging code to a BS. The BS
allocates a UL burst of a size of 6 bytes to the MS using a
CDMA_Allocation_IE. At this time, the MS transmits a band request header
omitting the HARQ CRC-16, to the BS. That is, the MS configures the band
request header to exclude the HARQ CRC-16 as shown in FIG. 5, and
transmits the band request header to the BS.

[0113] At this time, the BS determines whether an error occurs in the band
request header using a Header Check Sum (HCS) included in the band
request header. At this time, even when the band request header is not
received, the BS can recognize that the error occurs in the band request
header. If the error occurs in the band request header, the BS may
reallocate a UL resource to the MS as in step 109 of FIG. 1. At this
time, after initially allocating a UL resource for the band request
header to the MS, the BS can reallocate the UL resource for the band
request header only during 16 frames. Here, in a case where the BS
reallocates a resource using a CDMA_Allocation_IE, the BS may configure
the CDMA_Allocation_IE for reallocating the resource, as in Table 2
above.

[0114] As described above, exemplary embodiments of the present invention
have an advantage of being capable of minimizing a resource overhead due
to HARQ while increasing a range for a ranging service, by distinguishing
an MS supporting HARQ and an MS not supporting the HARQ and allocating a
resource for ranging in a BS of a wireless communication system.

[0115] While the invention has been shown and described with reference to
certain preferred embodiments thereof, it will be understood by those
skilled in the art that various changes in form and details may be made
therein without departing from the spirit and scope of the invention as
defined by the appended claims.